Large Ring Heterocycles: Template Synthesis and Structure

Abstract

One of the major differences between synthetic and natural ion carriers is the abundance of amide and lactone groups in the natural compounds. In order to shed light on the role of the carbonyl groups in these molecules, several series of macrocyclic polycarbonyl compounds have been prepared, and their conformations compared with those of the naturally occurring ionophores. The synthesis of these compounds was achieved via the use of cyclic silicon and tin derivatives as templates. The conformation of the macrocyclic products was determined both in solution and in the solid state. This structural comparison led to recognize the effect of ring symmetry on conformation, and to realize that the presence of rotational symmetry is a prerequisite for a macrocyclic polycarbonyl compound to simulate the conformation of natural ionophores.